Then it isn’t about education or schooling. You mention 3 things, values, communication and religion, not academics.
How late you stay up and what about Friday night, those are values issues and its your right and responsibility to teach your kids your values and help them develop their own. Can’t force them but you can put up a boundry. Learning to understand and communicate those boundries is critical to living in peace.
The church issue is really about teaching your kids how to differentiate between different religious systems. You happen to have a different religous belief system in your extended family. Most people do. At a certain point in my life I was curious about other systems and its good to learn the good and the bad. Knowing about them doesn’t change your values. It might make you question values but that just makes you stronger and smarter.
The discussion issue is just totally about having a great relationship with your kids. You are right. You are healthy. Grandparents should not undercut the relationship between the kids and the parent. Its unhealthy for the kids. If they want to have a close relationship with the kids then thats great. If the relationship means that the the kids will tell grama something that they wont tell you, you need to work on your relationship. It shouldn’t be encouraged but in some cases, its good that they are telling an adult in your family. Grama then has the responsibility to tell you to work on your communication with your kids, but not betray the kids confidence. And also, your relationship with your parents will be a model for your relationship with your kids, so fix that one to mirror what you want for them.
Now, my preaching has ended. Hugs and I have to say how lucky you are to still have your parents. How lucky they are to have relationships with their grandkids. Such an opportunity for love.